The following list from Hogarty's Lightroom Journal blog post details the issues found in Lightroom 1.4 and Camera Raw 4.4.

Lightroom

• Lightroom 1.4 incorrectly modified the EXIF time date field of images that had a metadata update applied. This incorrect modification does not appear in Lightroom or Bridge and is only viewable through third party EXIF tools. This error has been corrected in Lightroom 1.4.1 and all files in a Lightroom catalog that have been incorrectly modified will be corrected on their next metadata update. (Metadata can be updated by selecting the files in the Library grid view and choosing Command or CTRL + S to save and update the metadata.)

• Any conversion to DNG in Lightroom 1.4 (Windows Only) would cause the DNG file to become unreadable by Lightroom’s Develop Module or Camera Raw 4.4 in Photoshop. The issue has been corrected and files can be converted to DNG again in order to resolve the issue for existing files. Returning to the original native raw files is not necessary. The affected DNG files can be selected and converted again using the DNG • Converter 4.4.1 available at www.adobe.com/dng/. This process is not required but recommended to ensure that a correct validation value is stored within the DNG files.